Positively charged abrasives and negatively charged ionic oxidizers for polishing applications

Abstract

The present invention provides a chemical-mechanical polishing composition comprising (a) abrasive particles, (b) an ionic oxidizing agent, and (c) water, and having a pH of about 1 to about 7, wherein the abrasive particles have an isoelectric point greater than 8 and the ionic oxidizing agent is negatively charged at the pH of the chemical-mechanical polishing composition. The present invention also provides a method for chemical-mechanical polishing a substrate, particularly a substrate comprising a silicon carbide layer on its surface, using the composition.

Description

[Technical Field]

[0001]

[0001] Compositions and methods for planarizing or polishing the surface of a substrate are well known in the art. Polishing compositions (also called polishing slurries) typically contain an abrasive in a liquid carrier and are applied to a surface by contacting a polishing pad containing the polishing composition with the surface. Typical abrasives include silicon dioxide, cerium oxide, aluminum oxide, zirconium oxide, and tin oxide. Polishing compositions are typically used in combination with a polishing pad (such as a polishing cloth or abrasive disc). Instead of, or in addition to, being suspended in the polishing composition, the abrasive can also be incorporated into the polishing pad. [Background technology]

[0002]

[0002] Next-generation semiconductor devices introduce the use of materials with increased hardness and other desirable properties for high-power, high-temperature, and high-frequency operation applications. Such materials may include silicon carbide and / or silicon nitride. Of these materials, silicon carbide offers a desirable combination of electrical and thermophysical properties, including high service operating temperatures, excellent corrosion resistance, and high thermal properties. However, silicon carbide is much harder and chemically inert than other materials utilized in integrated circuits.

[0003]

[0003] In view of the above, polishing silicon carbide can be difficult and can result in low removal rates. As a result, conventional polishing compositions for polishing silicon carbide often use hard abrasives. While these hard abrasives can achieve substantially higher removal rates, they often result in increased scratching of the silicon carbide surface and poorer roughness characteristics.

[0004]

[0004] Therefore, there is a continuing need to develop new polishing methods and compositions that provide relatively high removal rates for silicon carbide and reduce the incidence of surface defects such as scratches and roughness. Summary of the Invention

[0005]

[0005] The present invention provides a chemical-mechanical polishing agent comprising (a) abrasive particles, (b) an ionic oxidizing agent, and (c) water, having a pH of about 1 to about 7 and an isoelectric point greater than 8, wherein the ionic oxidizing agent is negatively charged at the pH of the chemical-mechanical polishing composition.

[0006] The present invention further provides a method for polishing a substrate, the method comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical-mechanical polishing composition, the chemical-mechanical polishing composition comprising: (a) abrasive particles, (b) an ionic oxidizing agent, and (c) water, the chemical-mechanical polishing composition having a pH of about 1 to about 7, the abrasive particles having an isoelectric point greater than 8, and the ionic oxidizing agent being negatively charged at the pH of the chemical-mechanical polishing composition; (iv) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition; and (v) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate to polish at least a portion of the substrate. The present invention provides a method comprising: [Brief explanation of the drawings]

[0007] [Figure 1] 1 shows the removal rates (μm / hr) of silicon carbide (SiC) at 5.4 psi for the aluminum, silica, and zirconia particles described in Example 1. [Figure 2]

[0008] As described in Example 1, silicon carbide (SiC) removal rates (μm / hr) at 11 psi are shown for aluminum and ceria particles. [Figure 3]

[0009] 1 shows the zeta potential (mV) as a function of pH for silica particles A described in Example 2 and used in Example 3. [Figure 4]

[0010] 1 shows silicon carbide (SiC) removal rates (μm / hr) at pH 3.8 for Polishing Compositions 3A to 3G described in Example 3. [Figure 5]

[0011] 1 shows the silicon carbide (SiC) removal rates (μm / hr) of Polishing Composition 4A (invention) and Polishing Composition 4B (comparative example) described in Example 4. [Figure 6]

[0012] 1 shows the removal roughness average (nm) of silicon carbide (SiC) for polishing composition 4A (invention) and polishing composition 4B (comparative example) described in Example 4. [Figure 7]

[0013] 1 shows the incidence of silicon carbide (SiC) removal scratch marks for polishing composition 4A (the present invention) and polishing composition 4B (comparative example) described in Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0008]

[0014] The present invention provides a chemical-mechanical polishing agent comprising (a) abrasive particles, (b) an ionic oxidizing agent, and (c) water, having a pH of about 1 to about 7 and an isoelectric point greater than 8, wherein the ionic oxidizing agent is negatively charged at the pH of the chemical-mechanical polishing composition.

[0009]

[0015] The polishing composition comprises abrasive particles. As used herein, the terms "abrasive" and "abrasive particles" can be used interchangeably and can refer to any dispersion of abrasive particles. In other words, the terms "abrasive" and "abrasive particles" can be used interchangeably and can refer to (i) a plurality of a single type of abrasive or abrasive particles, or alternatively, (ii) a plurality of two or more types of abrasives or abrasive particles.

[0010]

[0016] The abrasive particles have an isoelectric point greater than 8. In other words, the abrasive particles have an isoelectric point higher than the pH of the chemical-mechanical polishing composition. As used herein, the term "isoelectric point" refers to the pH at which the abrasive particles carry no net charge or are electrically neutral on statistical average. The abrasive particles can have an isoelectric point of about 8.2 or higher, e.g., about 8.4 or higher, about 8.5 or higher, about 8.6 or higher, about 8.8 or higher, or about 9 or higher. Alternatively, or in addition, the abrasive particles can have an isoelectric point of about 12 or lower, e.g., about 11.5 or lower, about 11 or lower, about 10.5 or lower, about 10 or lower, about 9.5 or lower, or about 9 or lower. Thus, the abrasive particles can have an isoelectric point bounded by any two of the aforementioned endpoints, as needed.

[0011]

[0017] For example, in some embodiments, the abrasive particles have a molecular weight of about 8.2 to about 12, e.g., about 8.2 to about 11.5, about 8.2 to about 11, about 8.2 to about 10.5, about 8.2 to about 10, about 8.2 to about 9.5, about 8.2 to about 9, about 8.4 to about 12, about 8.4 to about 11.5, about 8.4 to about 11, about 8.4 to about 10.5, about 8.4 to about 10, about 8.4 to about 9.5, about 8.4 to about 9, about 8.5 to about 12, about 8.5 to about 11.5, about 8.5 to about 11, about 8.5 to about 10.5, about 8.5 to about 10, or about 8. The abrasive particles may have an isoelectric point of about 5 to about 9.5, about 8.5 to about 9, about 8.6 to about 12, about 8.6 to about 11.5, about 8.6 to about 11, about 8.6 to about 10.5, about 8.6 to about 10, about 8.6 to about 9.5, about 8.6 to about 9, about 8.8 to about 12, about 8.8 to about 11.5, about 8.8 to about 11, about 8.8 to about 10.5, about 8.8 to about 10, about 8.8 to about 9.5, about 8.8 to about 9, about 9 to about 12, about 9 to about 11.5, about 9 to about 11, about 9 to about 10.5, about 9 to about 10, or about 9 to about 9.5. In some embodiments, the isoelectric point of the abrasive particles is about 8.2 to about 11, or about 8.5 to about 10. In certain embodiments, the isoelectric point of the abrasive particles is from about 8.8 to about 9.5.

[0012]

[0018] The abrasive particles can be composed of any suitable metal and / or metalloid, so long as they are hard enough to provide a sufficient removal rate and soft enough to cause few surface defects (e.g., few scratches, good roughness quality, etc.). For example, the abrasive particles can include silica, zirconia, ceria, or a combination thereof. In some embodiments, the abrasive particles have a Mohs hardness of about 7 or less (e.g., about 6.8 or less, about 6.6 or less, about 6.4 or less, about 6.2 or less, about 6 or less, about 5.8 or less, or about 5.6 or less). In particular embodiments, the abrasive particles have a Mohs hardness of about 6 or less. Alternatively, or additionally, the abrasive particles have a Mohs hardness of about 3 or greater, e.g., about 3.5 or greater, about 4 or greater, about 4.5 or greater, or about 5 or greater. Thus, the abrasive particles can have a Mohs hardness limited by any two of the aforementioned endpoints, as desired.

[0013]

[0019] For example, in some embodiments, the abrasive particles have a molecular weight of about 3 to about 7, e.g., about 3.5 to about 7, about 4 to about 7, about 4.5 to about 7, about 5 to about 7, about 3 to about 6.8, about 3.5 to about 6.8, about 4 to about 6.8, about 4.5 to about 6.8, about 5 to about 6.8, about 3 to about 6.6, about 3.5 to about 6.6, about 4 to about 6.6, about 4.5 to about 6.6, about 5 to about The Mohs hardness may be 6.6, about 3 to about 6.4, about 3.5 to about 6.4, about 4 to about 6.4, about 4.5 to about 6.4, about 5 to about 6.4, about 3 to about 6.2, about 3.5 to about 6.2, about 4 to about 6.2, about 4.5 to about 6.2, about 5 to about 6.2, about 3 to about 6, about 3.5 to about 6, about 4 to about 6, about 4.5 to about 6, or about 5 to about 6.

[0014]

[0020] In some embodiments, the abrasive particles comprise metals and / or metalloids other than silicon, zirconium, or cerium. For example, the abrasive particles can further comprise aluminum (e.g., aluminum-doped or aluminum-coated). In some embodiments, the abrasive particles (e.g., silica particles or colloidal silica particles) are aluminum-doped and / or have a thin alumina coating.

[0015]

[0021] The abrasive particles (e.g., silica particles or colloidal silica particles) may be modified (e.g., surface-modified) or unmodified, and may have a negative or positive intrinsic zeta potential. As used herein, the phrase "native zeta potential" refers to the zeta potential of an abrasive prior to its addition to the polishing composition. For example, the native zeta potential may refer to the zeta potential of an abrasive particle measured in a storage solution or aqueous solution prior to its addition to the polishing composition.

[0016]

[0022] The charge on dispersed particles, such as abrasive particles (e.g., silica particles or colloidal silica particles), is commonly referred to as the zeta potential (or electrokinetic potential). The zeta potential of a particle refers to the potential difference between the charge of the ions surrounding the particle and the charge of the bulk solution of the composition being measured (e.g., the liquid carrier and other components dissolved therein). Zeta potential typically depends on the pH of the aqueous medium. For a particular polishing composition, the isoelectric point of the particle is defined as the pH at which the zeta potential is zero. As the pH increases or decreases from the isoelectric point, the surface charge (and therefore the zeta potential) decreases or increases accordingly (to negative or positive zeta potential values). Those skilled in the art will be able to determine whether an abrasive has a negative or positive intrinsic zeta potential before adding it to the polishing composition. The native zeta potential and zeta potential of a polishing composition can be obtained using a Model DT-1202 Acoustic and Electro-acoustic Spectrometer available from Dispersion Technologies, Inc. (Bedford Hills, NY). As used herein, the term "positive zeta potential" refers to a silica abrasive that exhibits a positive surface charge when measured in a polishing composition.

[0017]

[0023] Generally, the abrasive particles (e.g., silica particles or colloidal silica particles) have a positive zeta potential in the chemical-mechanical polishing composition. In other words, the abrasive particles have a zeta potential of greater than 0 mV in the chemical-mechanical polishing composition. In some embodiments, the abrasive particles have a zeta potential of greater than about +5 mV in the chemical-mechanical polishing composition, such as greater than about +10 mV, greater than about +15 mV, greater than about +20 mV, greater than about +25 mV, greater than about +30 mV, greater than about +35 mV, greater than about +40 mV, greater than about +45 mV, or greater than about +50 mV in the chemical-mechanical polishing composition. In some embodiments, the abrasive particles have a zeta potential of greater than about +10 mV in the chemical-mechanical polishing composition. In certain embodiments, the abrasive particles have a zeta potential of greater than about +20 mV in the chemical-mechanical polishing composition. In a preferred embodiment, the abrasive particles have a zeta potential of greater than about +40 mV in the chemical-mechanical polishing composition.

[0018]

[0024] In some embodiments, the abrasive particles comprise silica. In other words, the polishing composition can comprise a silica abrasive. As used herein, the terms "silica abrasive," "silica abrasive particles," "silica particles," and "abrasive particles" can be used interchangeably and can refer to any silica particles (e.g., colloidal silica particles).

[0019]

[0025] Silica abrasives (e.g., colloidal silica particles) may be modified (e.g., surface-modified) or unmodified, and may have a negative or positive intrinsic zeta potential. Thus, silica abrasives (e.g., colloidal silica particles) may have a positive or negative zeta potential before being added to the chemical-mechanical polishing composition. For example, silica particles (e.g., colloidal silica particles) may have a native zeta potential of less than 0 mV (e.g., −5 mV or less) before being added to the chemical-mechanical polishing composition. Alternatively, silica particles (e.g., colloidal silica particles) may have a native zeta potential of 0 mV or greater (e.g., 5 mV or greater) before being added to the chemical-mechanical polishing composition.

[0020]

[0026] Silica particles (e.g., colloidal silica particles) and charged silica particles (e.g., colloidal silica particles) can be prepared by various methods, some of which are commercially used and known. Useful silica particles include precipitated silica or condensation-polymerized silica, which can be prepared using known methods such as the so-called "sol-gel" method or the silicate ion exchange method. Condensation-polymerized silica particles are often prepared by condensing Si(OH)4 to form substantially spherical (e.g., spherical, ovoid, or rectangular) particles. The precursor Si(OH)4 can be obtained, for example, by hydrolysis of high-purity alkoxysilanes or by acidification of aqueous silicate solutions. U.S. Pat. No. 5,230,833 describes a method for preparing colloidal silica particles in solution.

[0021]

[0027] In some embodiments, the silica abrasive is colloidal silica. As known to those skilled in the art, colloidal silica is a suspension of fine, amorphous, non-porous, typically spherical particles in a liquid phase. Colloidal silica can be in the form of condensation-polymerized silica particles or precipitated silica particles. In some embodiments, the silica is in the form of wet-process silica particles. The particles, such as colloidal silica, can have any suitable average size (i.e., average particle diameter). If the average abrasive particle size is too small, the polishing composition may not exhibit a sufficient removal rate. In contrast, if the average abrasive particle size is too large, the polishing composition may exhibit undesirable polishing performance, such as a reduced substrate defect rate.

[0022]

[0028] Thus, the abrasive particles (e.g., silica particles or colloidal silica particles) can have an average particle size of about 10 nm or more, e.g., about 15 nm or more, about 20 nm or more, about 25 nm or more, about 30 nm or more, about 35 nm or more, about 40 nm or more, about 45 nm or more, or about 50 nm or more. Alternatively, or additionally, the abrasive particles (e.g., silica particles or colloidal silica particles) can have an average particle size of about 200 nm or less, e.g., about 175 nm or less, about 150 nm or less, about 125 nm or less, about 100 nm or less, about 75 nm or less, about 50 nm or less, or about 40 nm or less. Thus, the abrasive particles (e.g., silica particles or colloidal silica particles) can have an average particle size bounded by any two of the foregoing endpoints.

[0023]

[0029] For example, abrasive particles (e.g., silica particles or colloidal silica particles) can have an average particle size of about 10 nm to about 200 nm, about 20 nm to about 200 nm, about 20 nm to about 175 nm, about 20 nm to about 150 nm, about 25 nm to about 125 nm, about 25 nm to about 100 nm, about 30 nm to about 100 nm, about 30 nm to about 75 nm, about 30 nm to about 40 nm, or about 50 nm to about 100 nm. For non-spherical abrasive particles (e.g., silica particles or colloidal silica particles), the particle size is the diameter of the smallest sphere that encloses the particle. Abrasive particle size can be measured using any suitable technique, such as laser diffraction techniques. Suitable particle size measurement equipment is available, for example, from Malvern Instruments (Malvern, UK).

[0024]

[0030] Abrasive particles (e.g., silica particles or colloidal silica particles) are preferably colloidally stable in the polishing composition. The term colloid refers to a suspension of particles in a liquid carrier (e.g., water). Colloidal stability refers to the maintenance of that suspension over time. In the present invention, an abrasive is considered colloidally stable if, when the abrasive is placed in a 100 mL graduated cylinder and left unstirred for 2 hours, the difference between the particle concentration in the bottom 50 mL of the cylinder ([B] in g / mL) and the particle concentration in the top 50 mL of the cylinder ([T] in g / mL) divided by the initial particle concentration in the polishing composition ([C] in g / mL) is 0.5 or less (i.e., {[B]-[T]} / [C]≦0.5). More preferably, the value of [B]-[T] / [C] is 0.3 or less, and most preferably 0.1 or less.

[0025]

[0031] Abrasive particles (e.g., silica particles or colloidal silica particles) can be present in the polishing composition in any suitable amount. If the amount of abrasive contained in the polishing composition of the present invention is too low, the polishing rate may not be sufficient. In contrast, if the polishing composition contains too much abrasive, the polishing composition may exhibit undesirable polishing performance and / or may be less cost-effective and / or less stable. The polishing composition may contain about 10 wt% or less of abrasive particles (e.g., silica particles or colloidal silica particles), for example, about 9 wt% or less, about 8 wt% or less, about 7 wt% or less, about 6 wt% or less, about 5 wt% or less, about 4 wt% or less, about 3 wt% or less, about 2 wt% or less, about 1 wt% or less, about 0.9 wt% or less, about 0.8 wt% or less, about 0.7 wt% or less, about 0.6 wt% or less, or about 0.5 wt% or less of abrasive particles (e.g., silica particles or colloidal silica particles). Alternatively, or in addition, the polishing composition can include about 0.001 wt.% or more abrasive particles (e.g., silica particles or colloidal silica particles), for example, about 0.005 wt.% or more, about 0.01 wt.% or more, 0.05 wt.% or more, about 0.1 wt.% or more, about 0.2 wt.% or more, about 0.3 wt.% or more, about 0.4 wt.% or more, about 0.5 wt.% or more, or about 1 wt.% or more abrasive particles (e.g., silica particles or colloidal silica particles). Thus, the polishing composition can optionally include an amount of abrasive particles (e.g., silica particles or colloidal silica particles) limited by any two of the foregoing endpoints.

[0026]

[0032] For example, in some embodiments, the abrasive particles (e.g., silica particles or colloidal silica particles) are present in the polishing composition in an amount of from about 0.001% to about 10% by weight of the polishing composition, e.g., from about 0.001% to about 8% by weight, from about 0.001% to about 6% by weight, from about 0.001% to about 5% by weight, from about 0.001% to about 4% by weight, from about 0.001% to about 2% by weight, or from about 0.001% to about 4% by weight. 1% to about 1% by weight, about 0.01% to about 10% by weight, about 0.01% to about 8% by weight, about 0.01% to about 6% by weight, about 0.01% to about 5% by weight, about 0.01% to about 5% by weight 4% by weight, about 0.01% to about 2% by weight, about 0.01% to about 1% by weight, about 0.05% to about 10% by weight, about 0.05% to about 8% by weight, about 0.05% to about 6% by weight, about 0 .05% to about 5% by weight, about 0.05% to about 4% by weight, about 0.05% to about 2% by weight, about 0.05% to about 1% by weight, about 0.1% to about 10% by weight, about 0.1% to about 4% by weight 8% by weight, about 0.1% to about 6% by weight, about 0.1% to about 5% by weight, about 0.1% to about 4% by weight, about 0.1% to about 2% by weight, about 0.1% to about 1% by weight, about 0.5% by weight It can be present in an amount of about 10 wt%, about 0.5 wt% to about 8 wt%, about 0.5 wt% to about 5 wt%, about 0.5 wt% to about 4 wt%, about 0.5 wt% to about 2 wt%, about 0.5 wt% to about 1 wt%, about 1 wt% to about 10 wt%, about 1 wt% to about 8 wt%, about 1 wt% to about 6 wt%, about 1 wt% to about 5 wt%, about 1 wt% to about 4 wt%, or about 1 wt% to about 2 wt%. In some embodiments, the polishing composition comprises about 0.001 wt% to about 10 wt% abrasive particles (e.g., silica particles or colloidal silica particles). In certain embodiments, the polishing composition comprises about 0.05 wt% to about 5 wt% abrasive particles (e.g., silica particles or colloidal silica particles).

[0027]

[0033] The chemical-mechanical polishing composition includes an ionic oxidizing agent. The ionic oxidizing agent can be any suitable compound that has a negative charge at the pH of the chemical-mechanical polishing composition and is capable of oxidizing the substrate. For example, ionic oxidizing agents include oxone, ammonium cerium nitrate, periodates (e.g., sodium periodate, potassium periodate), iodates (e.g., sodium iodate, potassium iodate, ammonium iodate), persulfates (e.g., sodium persulfate, potassium persulfate, ammonium persulfate), chlorates (e.g., sodium chlorate, potassium chlorate), chromates (e.g., sodium chromate, potassium chromate), permanganates (e.g., sodium permanganate, potassium permanganate, ammonium permanganate), bromates (e.g., sodium bromate, potassium bromate), perbromates (e.g., sodium perbromate, potassium perbromate), ferrates (e.g., potassium ferrate), perrhenates (e.g., ammonium perrhenate), perruthenates (e.g., tetrapropylammonium perruthenate), or combinations thereof. The ionic oxidizing agent may be in the form of an acid (e.g., persulfate), a salt (e.g., ammonium persulfate), or a mixture thereof before being added to the chemical-mechanical polishing composition. In some embodiments, the ionic oxidizing agent comprises an alkali metal (e.g., sodium or potassium) salt of periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, or a combination thereof.

[0028]

[0034] In some embodiments, the ionic oxidizing agent is a periodate (e.g., sodium periodate or potassium periodate), a persulfate (e.g., sodium persulfate, potassium persulfate, or ammonium persulfate), a permanganate (e.g., sodium permanganate, potassium permanganate, or ammonium permanganate), or a combination thereof. In certain embodiments, the ionic oxidizing agent comprises potassium persulfate, potassium permanganate, periodic acid, or a combination thereof.

[0029]

[0035] The polishing composition can include any suitable amount of ionic oxidizing agent. The polishing composition can include about 20 wt% or less of ionic oxidizing agent, for example, about 15 wt% or less, about 10 wt% or less, about 9 wt% or less, about 8 wt% or less, about 7 wt% or less, about 6 wt% or less, about 5 wt% or less, about 4 wt% or less, about 3 wt% or less, or about 2 wt% or less of ionic oxidizing agent. Alternatively, or additionally, the polishing composition can include about 0.1 wt% or more of ionic oxidizing agent, for example, about 0.2 wt% or more, about 0.3 wt% or more, about 0.4 wt% or more, or about 0.5 wt% or more of ionic oxidizing agent. Thus, the polishing composition can optionally include an amount of ionic oxidizing agent limited by any two of the aforementioned endpoints.

[0030]

[0036] For example, in some embodiments, the ionic oxidizing agent can be present in the polishing composition in an amount of about 0.1 wt % to about 20 wt %, about 0.1 wt % to about 15 wt %, about 0.1 wt % to about 10 wt %, about 0.1 wt % to about 9 wt %, about 0.1 wt % to about 8 wt %, about 0.1 wt % to about 7 wt %, about 0.1 wt % to about 6 wt %, about 0.1 wt % to about 5 wt %, about 0.1 wt % to about 4 wt %, about 0.1 wt % to about 3 wt %, about 0.1 wt % to about 2 wt %, about 0.2 wt % to about 20 wt %, or about 0.2 wt %. About 15% by weight, about 0.2% to about 10% by weight, about 0.2% to about 9% by weight, about 0.2% to about 8% by weight, about 0.2% to about 7% by weight, about 0.2% to about 6% by weight , about 0.2% to about 5% by weight, about 0.2% to about 4% by weight, about 0.2% to about 3% by weight, about 0.2% to about 2% by weight, about 0.3% to about 20% by weight, about 0.3% by weight % to about 15% by weight, about 0.3% to about 10% by weight, about 0.3% to about 9% by weight, about 0.3% to about 8% by weight, about 0.3% to about 7% by weight, about 0.3% to about 6% by weight Amount%, about 0.3% to about 5% by weight, about 0.3% to about 4% by weight, about 0.3% to about 3% by weight, about 0.3% to about 2% by weight, about 0.4% to about 20% by weight, about 0.4 Weight% to about 15% by weight, about 0.4% to about 10% by weight, about 0.4% to about 9% by weight, about 0.4% to about 8% by weight, about 0.4% to about 7% by weight, about 0.4% to about 7% by weight 6% by weight, about 0.4% to about 5% by weight, about 0.4% to about 4% by weight, about 0.4% to about 3% by weight, about 0.4% to about 2% by weight, about 0.5% to about 20% by weight, about 0 The ionic oxidizing agent can be present in an amount of about 0.5 wt.% to about 15 wt.%, about 0.5 wt.% to about 10 wt.%, about 0.5 wt.% to about 9 wt.%, about 0.5 wt.% to about 8 wt.%, about 0.5 wt.% to about 7 wt.%, about 0.5 wt.% to about 6 wt.%, about 0.5 wt.% to about 5 wt.%, about 0.5 wt.% to about 4 wt.%, about 0.5 wt.% to about 3 wt.%, or about 0.5 wt.% to about 2 wt.%. In some embodiments, the polishing composition comprises about 0.1 wt.% to about 2 wt.% of the ionic oxidizing agent.

[0031]

[0037] The polishing composition includes water. The water may be any suitable water, such as deionized water or distilled water. In some embodiments, the polishing composition may further include one or more organic solvents in combination with water. For example, the polishing composition may further include a hydroxyl solvent, such as methanol or ethanol, a ketone solvent, an amide solvent, a sulfoxide solvent, or the like.

[0032]

[0038] The chemical-mechanical polishing composition has a pH of about 1 to about 7. In some embodiments, the polishing composition has a pH of about 6 or less, e.g., about 5.5 or less, about 5 or less, about 4.5 or less, or about 4 or less. Alternatively, or additionally, the polishing composition can have a pH of about 1 or greater, e.g., about 2 or greater, or about 3 or greater. Thus, the polishing composition can have a pH limited by any two of the aforementioned endpoints. For example, the polishing composition can have a pH of about 1 to about 6, e.g., about 1 to about 5.5, about 1 to about 5, about 1 to about 4.5, about 1 to about 4, about 2 to about 6, about 2 to about 5.5, about 2 to about 5, about 2 to about 4.5, about 2 to about 4, about 3 to about 6, about 3 to about 5.5, about 3 to about 5, about 3 to about 4.5, or about 3 to about 4. In some embodiments, the pH of the chemical-mechanical polishing composition is about 1 to about 5. In certain embodiments, the pH of the polishing composition is about 3 to about 5.

[0033]

[0039] The pH of the polishing composition can be adjusted using any suitable acid or base. Non-limiting examples of suitable acids include nitric acid, sulfuric acid, phosphoric acid, and organic acids such as formic acid and acetic acid. Non-limiting examples of suitable bases include sodium hydroxide, potassium hydroxide, and ammonium hydroxide.

[0034]

[0040] In some embodiments, the polishing composition further comprises a buffering agent. The buffering agent can be any suitable compound capable of buffering (e.g., maintaining) the polishing composition at a specific pH range. For example, the buffering agent can be selected from ammonium salts, alkali metal salts, alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, borates, amino acids, and combinations thereof.

[0035]

[0041] In some embodiments, the polishing composition further comprises an inorganic salt. The inorganic salt can be any suitable water-soluble inorganic salt. For example, the inorganic salt can be one or more inorganic salts selected from water-soluble bromides, chlorides, iodides, acetates, nitrates, sulfates, and combinations thereof. Without being bound by theory, it is believed that the inorganic salt can be used to increase the polishing rate of a substrate (e.g., silicon carbide). In some embodiments, the inorganic salt is an aluminum-based inorganic salt. For example, the inorganic salt can be aluminum sulfate, aluminum nitrate (e.g., aluminum nitrate hexahydrate), aluminum acetate, aluminum bromide, aluminum chloride, aluminum iodide, or a combination thereof. In some embodiments, the polishing composition further comprises aluminum nitrate (e.g., aluminum nitrate hexahydrate).

[0036]

[0042] The chemical-mechanical polishing composition optionally further comprises one or more additives, such as conditioners, acids (such as sulfonic acids), complexing agents, chelating agents, biocides, scale inhibitors, and dispersants.

[0037]

[0043] In some embodiments, the polishing composition further comprises a biocide. Non-limiting examples of suitable biocides include isothiazolinone-based biocides such as Kordek MLX™ (DuPont, Wilmington, Delaware). The polishing composition can include any suitable amount of biocide. For example, the polishing composition can include about 0.001 wt % to about 0.2 wt % of the biocide.

[0038]

[0044] In an embodiment, the invention provides a chemical-mechanical polishing composition comprising, consisting essentially of, or consisting of (a) abrasive particles, (b) an ionic oxidizing agent, and (c) water, wherein the chemical-mechanical polishing composition has a pH of about 1 to about 5, the abrasive particles have a high isoelectric point of greater than 8, and the ionic oxidizing agent is oxone, ammonium cerium nitrate, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, or a combination thereof.

[0039]

[0045] In an embodiment, the invention provides a chemical-mechanical polishing composition comprising, consisting essentially of, or consisting of (a) abrasive particles, (b) an ionic oxidizing agent, and (c) water, wherein the chemical-mechanical polishing composition has a pH of about 3 to about 5, the abrasive particles have a high isoelectric point greater than 8, and the ionic oxidizing agent is potassium persulfate, potassium permanganate, periodic acid, or a combination thereof.

[0040]

[0046] In an embodiment, the invention provides a chemical-mechanical polishing composition comprising, consisting essentially of, or consisting of (a) silica abrasive particles, (b) an ionic oxidizing agent, and (c) water, wherein the chemical-mechanical polishing composition has a pH of about 3 to about 5, the abrasive particles have a high isoelectric point greater than 8, and the ionic oxidizing agent is potassium persulfate, potassium permanganate, periodic acid, or a combination thereof.

[0041]

[0047] The polishing composition can be manufactured by any suitable technique, many of which are known to those skilled in the art. The polishing composition can be prepared in a batch or continuous manner. Generally, the polishing composition is prepared by combining the components of the polishing composition. As used herein, the term "component" includes not only individual components (e.g., abrasive particles, ionic oxidizers, optional pH adjusters, optional inorganic salts, and / or optional additives) but also any combination of components (e.g., abrasive particles, ionic oxidizers, optional pH adjusters, optional inorganic salts, and / or optional additives, etc.).

[0042]

[0048] For example, the polishing composition can be prepared by (i) providing all or part of a liquid carrier; (ii) dispersing abrasive particles, an ionic oxidizing agent, an optional pH adjuster, an optional inorganic salt, and / or any optional additives using any suitable means for preparing such a dispersion; (iii) adjusting the pH of the dispersion appropriately; and (iv) optionally adding appropriate amounts of other optional components and / or additives to the mixture.

[0043]

[0049] Alternatively, the polishing composition can be prepared by (i) providing one or more components (e.g., an ionic oxidizing agent, an optional pH adjuster, an optional inorganic salt, and / or optional additives) in a polishing slurry (e.g., a silica polishing slurry); (ii) providing one or more components (e.g., a liquid carrier, an ionic oxidizing agent, an optional pH adjuster, an optional inorganic salt, and / or optional additives) in an additive solution; (iii) combining the polishing slurry (e.g., a silica polishing slurry) with the additive solution to form a mixture; (iv) optionally adding appropriate amounts of other optional additives to the mixture; and (v) adjusting the pH of the mixture accordingly.

[0044]

[0050] The polishing composition can be supplied as a one-package system containing abrasive particles (e.g., silica abrasive particles), an ionic oxidizer, an optional pH adjuster, optional inorganic salts, and / or optional additives, and water. Alternatively, the polishing composition of the present invention can be supplied as a two-package system containing a polishing slurry (e.g., silica abrasive slurry) in a first package and an additive solution in a second package, where the polishing slurry (e.g., silica abrasive slurry) consists essentially of or consists of an abrasive (e.g., silica abrasive) and water, and the additive solution consists essentially of or consists of an ionic oxidizer, optional pH adjuster, optional inorganic salts, and / or optional additives. In the two-package system, the properties of the polishing composition can be adjusted by changing the mixing ratio of the two packages, i.e., the polishing slurry (e.g., silica abrasive slurry) and the additive solution.

[0045]

[0051] Various methods can be used to utilize such a two-package polishing system. For example, the polishing slurry (e.g., silica polishing slurry) and the additive solution can be supplied to the polishing table through separate pipes that are joined and connected at the outlet of the supply piping. The polishing slurry (e.g., silica polishing slurry) and the additive solution can be mixed shortly before or immediately before polishing, or can be supplied simultaneously onto the polishing table. Furthermore, when the two packages are mixed, deionized water can be added as needed to adjust the polishing composition and the resulting substrate polishing characteristics.

[0046]

[0052] Similarly, in connection with the present invention, three, four, or more packaging systems can be utilized, with each of the multiple containers containing a different component of the chemical mechanical polishing composition of the present invention, one or more optional components, and / or different concentrations of one or more of the same components.

[0047]

[0053] To mix components contained in two or more storage devices to produce a polishing composition at or near the point of use, the storage devices are typically provided with one or more flow lines leading from each storage device to the point of use of the polishing composition (e.g., a platen, a polishing pad, or a substrate surface). As used herein, the term "point of use" refers to the point at which the polishing composition is applied to the substrate surface (e.g., a polishing pad or the substrate surface itself). The term "flow line" refers to the flow path from an individual storage container to the point of use of the components stored therein. Each flow line can directly lead to the point of use, or two or more flow lines can be joined at any point to form a single flow line leading to the point of use. Furthermore, any of the flow lines (e.g., individual flow lines or combined flow lines) may first lead to one or more other devices (e.g., pumping devices, metering devices, mixing devices, etc.) before reaching the point of use of the component.

[0048]

[0054] The components of the polishing composition can be supplied independently to the point of use (e.g., the components are supplied to the substrate surface, where they are mixed during the polishing process), or one or more of the components can be combined before being supplied to the point of use, e.g., immediately before or immediately before being supplied to the point of use. Components are mixed "immediately before being supplied to the point of use" if they are mixed within about 5 minutes, e.g., within about 4 minutes, within about 3 minutes, within about 2 minutes, within about 1 minute, within about 45 seconds, within about 30 seconds, within about 10 seconds, or simultaneously with the supply of the components at the point of use (e.g., the components are mixed in a dispenser). Components are also combined "immediately before being supplied to the point of use" if they are combined within 5 m of the use location, e.g., within 1 m of the point of use, or within 10 cm of the point of use (e.g., within 1 cm of the point of use).

[0049]

[0055] When two or more components of the polishing composition are mixed before reaching the point of use, the components can be mixed in a flow line and delivered to the point of use without using a mixing device. Alternatively, one or more flow lines can lead to a mixing device to facilitate mixing of the two or more components. Any suitable mixing device can be used. For example, the mixing device can be a nozzle or jet (e.g., a high-pressure nozzle or jet) through which two or more components flow. Alternatively, the mixing device can be a container-type mixing device having one or more inlets through which two or more components of the polishing slurry are introduced into the mixer, and at least one outlet through which the mixed components exit the mixer and are delivered to the point of use directly or via other elements of the device (e.g., via one or more flow lines). Furthermore, the mixing device can have one or more chambers, each chamber having at least one inlet and at least one outlet, and two or more components are mixed in each chamber. When a container-type mixing device is used, it is preferable that the mixing device be equipped with a mixing mechanism to further facilitate mixing of the components. Mixing mechanisms are commonly known in the art and include stirrers, blenders, agitators, paddle baffles, gas sparger systems, vibrators, and the like.

[0050]

[0056] The polishing composition can also be provided as a concentrate intended to be diluted with an appropriate amount of water before use. In such embodiments, the polishing composition concentrate contains the components of the polishing composition in amounts such that, upon dilution of the concentrate with an appropriate amount of water, each component of the polishing composition is present in the polishing composition in an amount within the appropriate range described above for each component. For example, the abrasive particles (e.g., silica abrasive particles), ionic oxidizer, optional pH adjuster, optional inorganic salt, and / or optional additives can each be present in the concentrate in an amount that is about twice (e.g., about three, about four, or about five times) greater than the concentration described above for each component, such that, when the concentrate is diluted with an equal amount of water (e.g., 2 equivalents, 3 equivalents, or 4 equivalents, respectively), each component will be present in the polishing composition in an amount within the range described above for each component. Additionally, as will be understood by those skilled in the art, the concentrate can include an appropriate percentage of water present in the final polishing composition to ensure that the abrasive particles (e.g., silica abrasive particles), ionic oxidizer, optional pH adjuster, optional inorganic salt, and / or any additives are at least partially or completely dissolved in the concentrate.

[0051]

[0057] The present invention further provides a method for polishing a substrate, the method comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical-mechanical polishing composition comprising: (a) abrasive particles, (b) an ionic oxidizing agent, and (c) water, the chemical-mechanical polishing composition having a pH of about 1 to about 7, the abrasive particles having an isoelectric point greater than 8, and the ionic oxidizing agent being negatively charged at the pH of the chemical-mechanical polishing composition; (iv) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition; and (v) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate to polish at least a portion of the substrate. The present invention provides a method comprising:

[0052]

[0058] The chemical mechanical polishing composition can be used to polish any suitable substrate, and is particularly useful for polishing substrates comprising at least one layer (typically a surface layer) comprising silicon carbide. Suitable substrates include wafers used in the semiconductor industry. Wafers typically comprise or are composed of, for example, metals, metal oxides, metal nitrides, metal composites, metal alloys, low-dielectric materials, or combinations thereof. The method of the present invention is particularly useful for polishing substrates comprising silicon carbide, silicon nitride, and / or silicon oxide, for example, any one, two, or particularly all three of the aforementioned materials. In a preferred embodiment, the substrate comprises a silicon carbide layer on the surface of the substrate, and at least a portion of the silicon carbide layer on the surface of the substrate is polished to polish the substrate.

[0053]

[0059] In certain embodiments, the substrate comprises silicon carbide in combination with silicon nitride and / or silicon oxide. Consequently, in certain embodiments, the substrate further comprises a silicon nitride layer on the surface of the substrate, and at least a portion of the silicon nitride layer on the surface of the substrate is polished to form a polished substrate. Alternatively, or additionally, the substrate further comprises a silicon oxide layer on the surface of the substrate, and at least a portion of the silicon oxide layer on the surface of the substrate is polished to form a polished substrate.

[0054]

[0060] The silicon carbide can be any suitable silicon carbide, many forms of which are known in the art. The silicon carbide can have any suitable polytype. The silicon nitride can be any suitable silicon nitride. The silicon oxide can likewise be any suitable silicon oxide, many forms of which are known in the art. Suitable types of silicon oxide include tetraethyl orthosilicate (TEOS), borophosphosilicate glass (BPSG), plasma-enhanced tetraethyl orthosilicate (PETEOS), thermal oxide, undoped silicate glass, high-density plasma (HDP) oxide, and the like.

[0055]

[0061] The polishing composition of the present invention preferably exhibits a high removal rate when polishing a substrate comprising silicon carbide according to the method of the present invention. For example, when polishing a silicon wafer comprising a silicon carbide layer according to one embodiment of the present invention, the polishing composition preferably exhibits a removal rate of about 300 Å / min or more, for example, about 350 Å / min or more, about 400 Å / min or more, about 450 Å / min or more, about 500 Å / min or more, about 550 Å / min or more, about 600 Å / min or more, about 650 Å / min or more, about 700 Å / min or more, about 750 Å / min or more, about 800 Å / min or more, about 850 Å / min or more, about 900 Å / min or more, about 950 Å / min or more, about 1000 Å / min or more, about 1100 Å / min or more, about 1200 Å / min or more. Preferably, the polishing composition exhibits a silicon carbide removal rate of about 1300 Å / min or greater, about 1400 Å / min or greater, about 1500 Å / min or greater, about 1600 Å / min or greater, about 1700 Å / min or greater, about 1800 Å / min or greater, about 1900 Å / min or greater, about 2000 Å / min or greater, about 2100 Å / min or greater, about 2200 Å / min or greater, about 2300 Å / min or greater, about 2400 Å / min or greater, about 2500 Å / min or greater, about 2600 Å / min or greater, about 2700 Å / min or greater, about 2800 Å / min or greater, about 2900 Å / min or greater, or about 3000 Å / min or greater. In some embodiments, when polishing a silicon wafer including a silicon carbide layer according to one embodiment of the present invention, the polishing composition desirably exhibits a silicon carbide removal rate of about 500 Å / min or greater.

[0056]

[0062] In embodiments, when the substrate further comprises silicon oxide, the silicon oxide can be any suitable silicon oxide, many of which are known in the art. Suitable types of silicon oxide include, but are not limited to, borophosphosilicate glass (BPSG), tetraethyl orthosilicate (TEOS), plasma-enhanced tetraethyl orthosilicate (PETEOS), thermal oxide, undoped silicate glass, high-density plasma (HDP) oxide, etc. The chemical mechanical polishing composition of the present invention desirably exhibits a low removal rate when polishing a substrate comprising silicon oxide according to the method of the present invention. For example, when polishing a substrate comprising silicon oxide according to one embodiment of the present invention, the polishing composition desirably exhibits a silicon oxide removal rate of about 500 Å / min or less, for example, about 250 Å / min or less, about 200 Å / min or less, about 150 Å / min or less, about 100 Å / min or less, about 50 Å / min or less, about 25 Å / min or less, about 10 Å / min or less, or about 5 Å / min or less. In some embodiments, when polishing a substrate comprising silicon oxide (e.g., on the surface of the substrate) according to one embodiment of the present invention, the polishing composition desirably exhibits a silicon oxide removal rate of about 50 Å / min or less. In certain embodiments, the polishing composition exhibits an undetectably low silicon oxide removal rate. In certain embodiments, the polishing composition does not remove any silicon oxide (i.e., a removal rate of 0 Å / min). Thus, when used to polish a substrate comprising a silicon carbide layer and a silicon oxide layer (e.g., on the surface of the substrate), the polishing composition desirably exhibits selectivity for polishing the silicon carbide layer over the silicon oxide layer.

[0057]

[0063] In embodiments, when the substrate further comprises silicon nitride, the silicon nitride can be any suitable silicon nitride, many of which are known in the art. The chemical-mechanical polishing composition of the present invention desirably exhibits a low removal rate when polishing a substrate comprising silicon nitride (e.g., on the surface of a substrate) according to the method of the present invention. For example, when polishing a substrate comprising silicon nitride according to one embodiment of the present invention, the polishing composition desirably exhibits a silicon nitride removal rate of about 500 Å / min or less, e.g., about 250 Å / min or less, about 200 Å / min or less, about 150 Å / min or less, about 100 Å / min or less, about 50 Å / min or less, about 25 Å / min or less, about 10 Å / min or less, or about 5 Å / min or less. In some embodiments, when polishing a substrate comprising silicon nitride (e.g., on the surface of a substrate) according to one embodiment of the present invention, the polishing composition desirably exhibits a silicon nitride removal rate of about 50 Å / min or less. In certain embodiments, the polishing composition exhibits an undetectably low silicon nitride removal rate. In certain embodiments, the polishing composition does not remove silicon nitride at all (i.e., removal rate of 0 Å / min). Therefore, when used to polish a substrate including a silicon carbide layer and a silicon nitride layer, it is desirable for the polishing composition to exhibit selectivity for polishing the silicon carbide layer over the silicon nitride layer.

[0058]

[0064] The chemical mechanical polishing composition of the present invention can be tailored to provide effective polishing in a desired polishing range selectively for a specific thin-layer material while minimizing surface defects, imperfections, corrosion, erosion, and removal of the stop layer. Selectivity can be controlled to some extent by varying the relative concentrations of the components of the polishing composition. If desired, the chemical mechanical polishing composition of the present invention can be used to polish a substrate containing silicon carbide and silicon nitride on a surface layer of the substrate, and the chemical mechanical polishing composition provides a polishing selectivity ratio of silicon carbide to silicon nitride of about 5:1 or greater (e.g., about 10:1 or greater, about 15:1 or greater, about 25:1 or greater, about 50:1 or greater, about 100:1 or greater, or about 150:1 or greater). The chemical mechanical polishing composition of the present invention can also be used to polish substrates containing silicon carbide and silicon oxide on the surface thereof, and the chemical mechanical polishing composition provides a polishing selectivity of silicon carbide to silicon oxide of about 5:1 or greater (e.g., about 10:1 or greater, about 15:1 or greater, about 25:1 or greater, about 50:1 or greater, about 100:1 or greater, or about 150:1 or greater). Thus, in embodiments, when used to polish a substrate containing at least one silicon carbide layer and at least one silicon nitride layer and / or at least one silicon oxide layer, the polishing composition and polishing method enable preferential removal of silicon carbide compared to removal of silicon nitride and / or silicon oxide. As used herein, the phrase "polishing selectivity" refers to the ratio of the removal rates of two different thin-layer materials.

[0059]

[0065] The polishing composition of the present invention desirably has low particle defects when polishing a substrate, as determined by a suitable technique. The particle defects on a substrate polished with the polishing composition of the present invention can be determined by any suitable technique. For example, laser light scattering techniques such as dark-field normal beam composite (DCN) and dark-field oblique beam composite (DCO) can be used to determine particle defects on the polished substrate. Suitable metrology instruments for evaluating particle defects are available, for example, from KLA-Tencor (e.g., SURFSCAN™ SPI metrology instruments operating at a threshold of 120 nm or 160 nm).

[0060]

[0066] The chemical mechanical polishing composition and method of the present invention are particularly suitable for use in combination with a chemical mechanical polishing apparatus. Typically, this apparatus includes a platen that is in motion during use and has a velocity resulting from orbital, linear, or circular motion, a polishing pad that contacts the platen and moves with the platen when in motion, and a carrier that holds a substrate to be polished by contacting and moving the substrate against the surface of the polishing pad. The substrate is polished by contacting the substrate with the polishing pad and the polishing composition of the present invention, and then moving the polishing pad relative to the substrate to polish at least a portion of the substrate.

[0061]

[0067] The substrate can be polished with the chemical mechanical polishing composition using any suitable polishing pad (e.g., polishing surface). Suitable polishing pads include, for example, woven and nonwoven polishing pads. Furthermore, suitable polishing pads can include any suitable polymer having various densities, hardnesses, thicknesses, compressibility, rebound capacity upon compression, and compressive moduli. Suitable polymers include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, fluorocarbon, polycarbonate, polyester, polyacrylate, polyether, polyethylene, polyamide, polyurethane, polystyrene, polypropylene, co-forms thereof, and mixtures thereof. Soft polyurethane polishing pads are particularly useful in combination with the polishing method of the present invention. Representative pads include SURFIN™ 000, SURFIN™ SSW1, SPM3100 (available from Emininess Technologies, etc.), POLITEX™, EPIC™ D100 pads (available from CMC Materials), IC1010 pads (available from Dow, Inc.), Fujibo POLYPAS™ 27, and the like.

[0062]

[0068] Preferably, the chemical mechanical polishing apparatus further includes an in situ polishing endpoint detection system, many of which are known in the art. Techniques for inspecting and monitoring the polishing process by analyzing light or other radiation reflected from the surface of the substrate being polished are known in the art. Such methods are described, for example, in U.S. Pat. Nos. 5,196,353, 5,433,651, 5,609,511, 5,643,046, 5,658,183, 5,730,642, 5,838,447, 5,872,633, 5,893,796, 5,949,927, and 5,964,643. Desirably, inspecting or monitoring the progress of the polishing process with respect to the substrate being polished allows for determining the polishing endpoint, i.e., when to terminate the polishing process with respect to a particular substrate.

[0063]

[0069] In an embodiment, the invention provides a method for polishing a substrate, comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical-mechanical polishing composition comprising, consisting essentially of, or alternatively consisting of: (a) abrasive particles; (b) an ionic oxidizing agent; and (c) water, wherein the chemical-mechanical polishing composition has a pH of about 1 to about 5; the abrasive particles have an isoelectric point greater than 8; and the ionic oxidizing agent is oxone, ammonium cerium nitrate, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, or a combination thereof; (iv) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition; and (v) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate to polish at least a portion of the substrate. The present invention provides a method comprising:

[0064]

[0070] In an embodiment, the invention provides a method for polishing a substrate, comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical-mechanical polishing composition comprising, consisting essentially of, or alternatively consisting of: (a) abrasive particles; (b) an ionic oxidizing agent; and (c) water, wherein the chemical-mechanical polishing composition has a pH of about 3 to about 5; the abrasive particles have an isoelectric point greater than 8; and the ionic oxidizing agent is potassium persulfate, potassium permanganate, periodic acid, or a combination thereof; (iv) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition; and (v) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate to polish at least a portion of the substrate. The present invention provides a method comprising:

[0065]

[0071] In an embodiment, the invention provides a method for polishing a substrate, comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical-mechanical polishing composition comprising, consisting essentially of, or alternatively consisting of: (a) silica abrasive particles; (b) an ionic oxidizing agent; and (c) water, wherein the chemical-mechanical polishing composition has a pH of about 1 to about 5, the abrasive particles have an isoelectric point greater than 8, and the ionic oxidizing agent is potassium persulfate, potassium permanganate, periodic acid, or a combination thereof; (iv) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition; and (v) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate to polish at least a portion of the substrate. The present invention provides a method comprising:

[0066]

[0072] Aspects of the present invention described herein, including embodiments, may be beneficial alone or in combination with one or more other aspects or embodiments. Without limiting the foregoing, certain non-limiting embodiments of the present disclosure, numbered 1 through 37, are provided below. As will be apparent to one of ordinary skill in the art upon reading this disclosure, each individually numbered embodiment can be used or combined with any of the preceding or subsequent individually numbered embodiments. This is intended to support all combinations of embodiments, and is not limited to the combinations of embodiments explicitly provided below.

[0067] Embodiment

[0073] (1) In embodiment (1), (a) abrasive particles; (b) Ionic oxidizing agents and (c) Water and Including, A chemical-mechanical polishing composition is provided, wherein the chemical-mechanical polishing composition has a pH of about 1 to about 7, the abrasive particles have an isoelectric point greater than 8, and the ionic oxidizing agent is negatively charged at the pH of the chemical-mechanical polishing composition.

[0068]

[0074] (2) In embodiment (2), the polishing composition of embodiment (1) is provided, wherein the polishing composition has a pH of about 1 to about 5.

[0069]

[0075] (3) In embodiment (3), the polishing composition of embodiment (1) or embodiment (2) is provided, wherein the polishing composition has a pH of about 3 to about 5.

[0070]

[0076] (4) In embodiment (4), there is provided the polishing composition of any one of embodiments (1) to (3), wherein the polishing composition comprises about 0.001 wt % to about 10 wt % abrasive particles.

[0071]

[0077] (5) In embodiment (5), there is provided the polishing composition according to any one of embodiments (1) to (4), wherein the polishing composition contains about 0.05 wt % to about 5 wt % of abrasive particles.

[0072]

[0078] (6) In embodiment (6), there is provided the polishing composition of any one of embodiments (1) to (5), wherein the abrasive particles have a Mohs hardness of about 7 or less.

[0073]

[0079] (7) In embodiment (7), there is provided the polishing composition according to any one of embodiments (1) to (6), wherein the abrasive particles have a Mohs hardness of about 6 or less.

[0074]

[0080] (8) In embodiment (8), there is provided the polishing composition according to any one of embodiments (1) to (7), wherein the abrasive particles have an isoelectric point of about 8.2 to about 11.

[0075]

[0081] (9) In embodiment (9), the polishing composition according to any one of embodiments (1) to (8) is provided, wherein the abrasive particles have an isoelectric point of about 8.5 to about 10.

[0076]

[0082] (10) In embodiment (10), there is provided the polishing composition according to any one of embodiments (1) to (9), wherein the abrasive particles have an isoelectric point of about 8.8 to about 9.5.

[0077]

[0083] (11) In embodiment (11), there is provided the polishing composition of any one of embodiments (1) to (10), wherein the abrasive particles comprise silica, zirconia, ceria, or a combination thereof.

[0078]

[0084] (12) In embodiment (12), there is provided the polishing composition of any one of embodiments (1) to (11), wherein the abrasive particles comprise silica.

[0079]

[0085] (13) In embodiment (13), the polishing composition of any one of embodiments (1) to (12) is provided, wherein the abrasive particles comprise surface-modified colloidal silica.

[0080]

[0086] (14) In embodiment (14), the polishing composition of any one of embodiments (1) to (13) is provided, wherein the ionic oxidizing agent is oxone, ammonium cerium nitrate, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, or a combination thereof.

[0081]

[0087] (15) In embodiment (15), the polishing composition according to any one of embodiments (1) to (14) is provided, wherein the ionic oxidizing agent is a periodate, a persulfate, a permanganate, or a combination thereof.

[0082]

[0088] (16) In embodiment (16), the polishing composition according to any one of embodiments (1) to (15) is provided, wherein the ionic oxidizing agent is potassium persulfate, potassium permanganate, periodic acid, or a combination thereof.

[0083]

[0089] (17) In embodiment (17), there is provided the polishing composition of any one of embodiments (1) to (16), wherein the polishing composition further comprises a buffering agent.

[0084]

[0090] (18) In embodiment (18), there is provided the polishing composition of any one of embodiments (1) to (17), wherein the polishing composition further comprises an inorganic salt.

[0085]

[0091] (19) In embodiment (19), the polishing composition of embodiment (18) is provided, wherein the inorganic salt is an aluminum-based inorganic salt.

[0086]

[0092] (20) In embodiment (20), a method for chemical mechanical polishing a substrate is provided, the method comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical-mechanical polishing composition, the chemical-mechanical polishing composition comprising: (a) abrasive particles; (b) an ionic oxidizing agent, and (c) water Including, providing a chemical-mechanical polishing composition having a pH of about 1 to about 7, wherein the abrasive particles have an isoelectric point greater than 8, and the ionic oxidizing agent is negatively charged at the pH of the chemical-mechanical polishing composition; (iv) contacting the substrate with a polishing pad and a chemical-mechanical polishing composition; (v) polishing at least a portion of the substrate and moving the polishing pad and chemical-mechanical polishing composition relative to the substrate to polish the substrate; Includes:

[0087]

[0093] (21) In embodiment (21), the method of embodiment (20) is provided, wherein the polishing composition has a pH of about 1 to about 5.

[0088]

[0094] (22) In embodiment (22), the method of embodiment (20) or embodiment (21) is provided, wherein the polishing composition has a pH of about 3 to about 5.

[0089]

[0095] (23) In embodiment (23), the method of any one of embodiments (20) to (22) is provided, wherein the polishing composition comprises about 0.001 wt % to about 10 wt % abrasive particles.

[0090]

[0096] (24) In embodiment (24), the method of any one of embodiments (20) to (23) is provided, wherein the polishing composition comprises about 0.05 wt % to about 5 wt % abrasive particles.

[0091]

[0097] (25) In embodiment (25), the method of any one of embodiments (20)-(24) is provided, wherein the abrasive particles have a Mohs hardness of about 7 or less.

[0092]

[0098] (26) In embodiment (26), the method of any one of embodiments (20)-(25) is provided, wherein the abrasive particles have a Mohs hardness of about 6 or less.

[0093]

[0099] (27) In embodiment (27), the method of any one of embodiments (20) to (26) is provided, wherein the abrasive particles have an isoelectric point of about 8.2 to about 11.

[0094]

[0100] (28) In embodiment (28), the method of any one of embodiments (20) to (27) is provided, wherein the abrasive particles have an isoelectric point of about 8.5 to about 10.

[0095]

[0101] (29) In embodiment (29), the method of any one of embodiments (20) to (28) is provided, wherein the abrasive particles have an isoelectric point of about 8.8 to about 9.5.

[0096]

[0102] (30) In embodiment (30), the method of any one of embodiments (20)-(29) is provided, wherein the abrasive particles comprise silica, zirconia, ceria, or a combination thereof.

[0097]

[0103] (31) In embodiment (31), the method of any one of embodiments (20)-(30) is provided, wherein the abrasive particles comprise silica.

[0098]

[0104] (32) In embodiment (32), the method of any one of embodiments (20)-(31) is provided, wherein the abrasive particles comprise surface-modified colloidal silica.

[0099]

[0105] (33) In embodiment (33), the method of any one of embodiments (20) to (32) is provided, wherein the ionic oxidizing agent is oxone, cerium ammonium nitrate, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, or a combination thereof.

[0100]

[0106] (34) In embodiment (34), the method of any one of embodiments (20) to (33) is provided, wherein the ionic oxidizing agent is periodate, persulfate, permanganate, or a combination thereof.

[0101]

[0107] (35) In embodiment (35), the method of any one of embodiments (20) to (34) is provided, wherein the ionic oxidizing agent is potassium persulfate, potassium permanganate, periodic acid, or a combination thereof.

[0102]

[0108] (36) In embodiment (36), the method of any one of embodiments (20) to (35) is provided, wherein the polishing composition further comprises a buffering agent.

[0103]

[0109] (37) In embodiment (37), the method of any one of embodiments (20) to (36) is provided, wherein the polishing composition further comprises an inorganic salt.

[0104]

[0110] (38) In embodiment (38), the method of embodiment (37) is provided, wherein the inorganic salt is an aluminum-based inorganic salt.

[0105]

[0111] (39) In embodiment (39), the method of any one of embodiments (20) to (38) is provided, wherein the substrate includes a silicon carbide layer on a surface of the substrate, and at least a portion of the silicon carbide layer on the surface of the substrate is polished to polish the substrate.

[0106]

[0112] (40) In embodiment (40), the method of embodiment (39) is provided, wherein the substrate further comprises a silicon nitride layer on the surface of the substrate, and at least a portion of the silicon nitride layer on the surface of the substrate is polished to polish the substrate.

[0107]

[0113] (41) In embodiment (41), the method of embodiment (39) or embodiment (40) is provided, wherein the substrate further comprises a silicon oxide layer on a surface of the substrate, and at least a portion of the silicon oxide on the surface of the substrate is polished to polish the substrate.

[0108] Example

[0114] The following examples further illustrate the invention but, of course, should not be construed as in any way limiting its scope.

[0109]

[0115] The following abbreviations are used throughout the examples: removal rate (RR), silicon carbide (SiC), root mean square (RMS), roughness average (RA), isoelectric point (IEP), zeta potential (ZP), and molecular weight (MW).

[0110]

[0116] In the following examples, SiC was coated on silicon, and the resulting patterned substrate was polished using a SPEEDFAM™ 32B benchtop polisher (50 rpm, 60-minute polishing time, 125 mL / min flow rate) and a Suba pad conditioned with a product commercially identified as A82 (3M, St. Paul, Minnesota). Removal rates were calculated by measuring film thickness using spectroscopic ellipsometry and subtracting the final thickness from the initial thickness.

[0111] Example 1

[0117] This example shows the silicon carbide removal rates of alumina, silica, zirconia, and ceria abrasives at various pH values ​​above and below their isoelectric points when used in combination with an ionic oxidizer such as potassium permanganate (KMnO).

[0112]

[0118] Aqueous polishing compositions containing 0.4 wt. % potassium permanganate (KMnO), 0.15 wt. % aluminum nitrate hexahydrate, and 0.6 wt. % of alumina (i.e., alpha alumina with a dynamic light scattering particle size of 120 nm), silica (i.e., surface-modified colloidal silica with a thin alumina coating and a dynamic light scattering particle size of 110 nm), zirconia (i.e., zirconia particles with a dynamic light scattering particle size of 180 nm), or ceria (i.e., ceria particles with a dynamic light scattering particle size of 110 nm) were prepared. The pH of each polishing composition was adjusted to 2, 3.8, 6, or 10.3 using nitric acid as the acid and potassium hydroxide as the base, as appropriate.

[0113]

[0119] Aqueous polishing compositions containing alumina particles, silica particles, and zirconia particles with pH values ​​of 2, 3.8, 6, and / or 10.3 were used to polish silicon carbide (SiC) at a downforce of 5.4 psi using a MAT AWR-681MS polisher and a POWER1000 polishing pad, and the resulting removal rates (μm / hr) are shown in Figure 1. Similarly, aqueous polishing compositions containing alumina particles and ceria particles with pH values ​​of 2, 3.8, and / or 6 were used to polish silicon carbide (SiC) at a downforce of 11 psi using a MAT AWR-681MS polisher and a POWER1000 polishing pad, and the resulting removal rates (μm / hr) are shown in Figure 2.

[0114]

[0120] As is evident from the results shown in Figures 1 and 2, aqueous polishing compositions containing alumina, silica, zirconia, and ceria all exhibited desirable silicon carbide removal rates at lower pH values, preferably below their IEPs, when used in combination with potassium permanganate (KMnO).

[0115] Example 2

[0121] This example demonstrates the isoelectric point of surface-modified colloidal silica with a thin alumina coating and a dynamic light scattering particle size of 110 nm.

[0116]

[0122] Silica particles A were added to the aqueous solution, and the pH was slowly adjusted from 2 to 10.5 using nitric acid as the acid and potassium hydroxide as the base, as appropriate. The zeta potential (ZP) of silica particles A was measured at various pH values ​​using a Model DT-1202 acoustic and electroacoustic spectrometer manufactured by Dispersion Technologies, Inc. (Bedford Hills, NY), and the results are shown in Figure 3 .

[0117]

[0123] As is clear from the results shown in FIG. 3, silica particles A had an IEP of about 9 and a zeta potential of about 20 mV or more in all cases where the pH value was less than 8.

[0118] Example 3

[0124] This example demonstrates the removal rate of silicon carbide obtained with a polishing composition comprising abrasive particles and an ionic oxidizing agent, where the abrasive particles have an isoelectric point greater than 8.

[0119]

[0125] An aqueous polishing slurry containing 0.4 wt. % potassium permanganate (KMnO4), 0.15 wt. % aluminum nitrate hexahydrate, and 0.6 wt. % silica or alumina particles was prepared as follows. Polishing Composition 3A (Invention) - Silica Particles A (from Example 2), which is a surface-modified colloidal silica having a thin alumina coating, a positive intrinsic zeta potential, and a dynamic light scattering particle size of 110 nm. Polishing Composition 3B (comparative) - Alpha alumina having a positive intrinsic zeta potential and a dynamic light scattering particle size of 120 nm. Polishing Composition 3C (comparative) - Aluminum-doped surface-modified colloidal silica having a negative intrinsic zeta potential and a dynamic light scattering particle size of 45 nm. Polishing Composition 3D (comparative) - Colloidal silica with a negative intrinsic zeta potential and a dynamic light scattering particle size of 53 nm. Polishing Composition 3E (comparative) - Aluminum-doped surface-modified colloidal silica having a negative intrinsic zeta potential and a dynamic light scattering particle size of 160 nm. Polishing Composition 3F (comparative) - transition alumina particles having a positive intrinsic zeta potential and a dynamic light scattering particle size of 55 nm. Polishing Composition 3G (comparison) - Fumed silica particles having a negative native zeta potential and a dynamic light scattering particle size of 120 nm.

[0120]

[0126] The pH of Polishing Compositions 3A to 3G was adjusted to 3.8, and each polishing composition was used to polish silicon carbide (SiC) using a MAT AWR-681MS polisher and a POWER1000 polishing pad at a downforce of 9 psi. The removal rate (μm / hr) results are shown in Table 1 and plotted in Figure 4. TIFF2025541983000002.tif77170

[0121]

[0127] As is evident from the results shown in Table 1 and Figure 4, polishing composition 3A of the present invention containing silica particles A (Example 2) exhibited a silicon carbide removal rate comparable to the highest silicon carbide removal rate exhibited by comparative polishing composition 3B containing alpha alumina having a positive intrinsic zeta potential and a dynamic light scattering particle size of 120 nm. Furthermore, polishing composition 3A of the present invention containing silica particles A (from Example 2) exhibited a silicon carbide removal rate higher than all other polishing compositions tested (i.e., comparative polishing compositions 3C-3G).

[0122] Example 4

[0128] This example illustrates the removal rate and surface defects of silicon carbide obtained with a polishing composition comprising abrasive particles and an ionic oxidizing agent, wherein the abrasive particles have an isoelectric point greater than 8.

[0123]

[0129] An aqueous polishing slurry containing 0.4 wt. % potassium permanganate (KMnO4), 0.15 wt. % aluminum nitrate hexahydrate, and 0.6 wt. % silica or alumina particles was prepared as follows. Polishing Composition 4A (Invention) - A thin alumina coating, surface modified colloidal silica with a positive intrinsic zeta potential and a dynamic light scattering particle size of 32 nm. Polishing Composition 4B (comparative) - Alpha alumina having a positive intrinsic zeta potential and a dynamic light scattering particle size of 120 nm.

[0124]

[0130] The pH of Polishing Compositions 4A and 4B was adjusted to 3.8, and each polishing composition was used to polish silicon carbide (SiC) using a SPEEDFAM™ 32B polisher and a SUBA™ polishing pad at a downforce of 5.63 psi. The removal rate (μm / hr) results are shown in Table 2 and plotted in FIG. 5, the roughness average (nm) results are shown in Table 2 and plotted in FIG. 6, and the scratch incidence rate (scratch count) results are shown in Table 2 and plotted in FIG. 7. TIFF2025541983000003.tif45170

[0125]

[0131] As is clear from the results shown in Table 2 and Figures 5 to 7, the polishing composition 4A of the present invention, which contains a thin alumina coating and a surface-modified colloidal silica having a positive intrinsic zeta potential, exhibited a silicon carbide removal rate and average surface roughness comparable to those exhibited by the comparative polishing composition 4B, but the surface scratches produced by polishing with the polishing composition 4A of the present invention were much fewer than those produced by polishing with the comparative polishing composition 4B. In other words, the polishing composition 4A of the present invention, which contains a thin alumina coating and a surface-modified colloidal silica having a positive intrinsic zeta potential, exhibited a polishing rate comparable to that of the comparative polishing composition 4B, with the advantage of fewer surface defects.

[0126]

[0132] All references cited herein, including publications, patent applications, and patents, are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0127]

[0133] In the context of describing the invention (particularly in the context of the claims below), use of the terms "a," "an," "the," and "at least one" and similar referents are to be construed as including both the singular and the plural, unless otherwise stated herein or clearly contradicted by context. When the term "at least one" is followed by a list of one or more items (e.g., "at least one of A and B"), it is to be construed as meaning one item selected from the listed items (A or B) or two or more of the listed items (A and B) in combination, unless otherwise stated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to") unless otherwise indicated. The recitation of ranges of values ​​is merely intended to serve as a shorthand method of referring individually to each separate value within that range, unless otherwise stated herein, and it will be understood that each separate value is incorporated into the specification as if each separate value were individually set forth herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. Any examples provided herein, or the use of exemplary language (e.g., "such as"), are solely for the purpose of improving the understanding of the invention and do not impose limitations on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0128]

[0134] Preferred embodiments of the invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of these preferred embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors expect skilled artisans to adopt such variations as necessary, and it is intended that the invention be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, the invention includes any combination of the above-described elements in all possible variations thereof unless otherwise indicated herein or clearly contradicted by context.

Claims

1. 1. A chemical-mechanical polishing composition comprising: (a) about 0.001% to about 10% by weight of abrasive particles, the abrasive particles having a Mohs hardness of about 7 or less; (b) an ionic oxidizing agent that is oxone, cerium ammonium nitrate, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, or a combination thereof; (c) water and Including, 1. A chemical-mechanical polishing composition, wherein the chemical-mechanical polishing composition has a pH of about 1 to about 7, the abrasive particles have an isoelectric point greater than 8, and the ionic oxidizing agent is negatively charged at the pH of the chemical-mechanical polishing composition.

2. 10. The polishing composition of claim 1, wherein the abrasive particles have an isoelectric point of about 8.2 to about 11.

3. 10. The polishing composition of claim 1, wherein the polishing composition has a pH of about 3 to about 5.

4. 10. The polishing composition of claim 1, wherein the polishing composition comprises about 0.05% to about 5% by weight of abrasive particles.

5. 10. The polishing composition of claim 1, wherein the abrasive particles have an isoelectric point of about 8.5 to about 10.

6. 10. The polishing composition of claim 1, wherein the abrasive particles have an isoelectric point of about 8.8 to about 9.

5.

7. The polishing composition of claim 1 , wherein the abrasive particles comprise silica, zirconia, ceria, or a combination thereof.

8. The polishing composition of claim 1 , wherein the abrasive particles comprise surface-modified colloidal silica.

9. 2. The polishing composition of claim 1, wherein the ionic oxidizing agent is potassium persulfate, potassium permanganate, periodic acid, or a combination thereof.

10. The polishing composition of claim 1 further comprising a buffering agent.

11. The polishing composition of claim 1 further comprising an inorganic salt.

12. The polishing composition of claim 11 , wherein the inorganic salt is an aluminum-based inorganic salt.

13. 1. A method of chemical mechanical polishing a substrate, comprising: (i) providing a substrate; (ii) providing a polishing pad; (iii) providing a chemical-mechanical polishing composition, the chemical-mechanical polishing composition comprising: (a) abrasive particles having a Mohs hardness of about 7 or less; (b) an ionic oxidizing agent, and (c) water and Including, providing a chemical-mechanical polishing composition having a pH of about 1 to about 7, wherein the abrasive particles have an isoelectric point greater than 8, and wherein the ionic oxidizing agent is negatively charged at the pH of the chemical-mechanical polishing composition; (iv) contacting the substrate with a polishing pad and a chemical-mechanical polishing composition; (v) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate to polish at least a portion of the substrate; and A method comprising:

14. The method of claim 13, wherein the polishing composition has a pH of about 3 to about 5.

15. The method of claim 13, wherein the polishing composition comprises from about 0.001% to about 10% by weight of abrasive particles.

16. The method of claim 13, wherein the polishing composition comprises about 0.05% to about 5% by weight of abrasive particles.

17. 14. The method of claim 13, wherein the abrasive particles have a Mohs hardness of about 6 or less.

18. The method of claim 13, wherein the abrasive particles have an isoelectric point of about 8.5 to about 10.

19. The method of claim 13 , wherein the abrasive particles comprise silica, zirconia, ceria, or a combination thereof.

20. 20. The method of claim 19, wherein the abrasive particles comprise surface-modified colloidal silica.

21. 14. The method of claim 13, wherein the ionic oxidizing agent is oxone, cerium ammonium nitrate, periodate, iodate, persulfate, chlorate, chromate, permanganate, bromate, perbromate, ferrate, perrhenate, perruthenate, or a combination thereof.

22. The method of claim 13 , wherein the polishing composition further comprises an inorganic salt, and the inorganic salt is an aluminum-based inorganic salt.

23. The method of claim 13 , wherein the substrate includes a silicon carbide layer on a surface of the substrate, and at least a portion of the silicon carbide layer on the surface of the substrate is polished to polish the substrate.

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